CFD work

[Peter-RC]

Hello,

Are there any members here who want to do some CFD work or other members?
I've seen CFDRuss topic, but his last visit was like 2005...

For me, i'm looking for somebody who can run some tests of a single element rear wing that i want to use on my radio controlled 1:8 scale on-road car.
Everybody in the R/C world says it doesn't work, but they can't say why.
I just like to have first hand experience instead of following the herd

Is there somebody who can help me with this?

[747heavy]

I can´t help with the CFP work Peter - sorry, but one reason for the "opinion" of your friends, is probably related to area (F=P*A) and to the "relative" low speeds of an RC-car. (in relation to F1/LMP).
So the gain in downforce, for such a small wing is probably very little, even in relation to the lower weight of your model car.
The question is, is it worth the effort, and what is the gain with your kind of tires ( I dunno).
But there is no reason, why a proper wing would not work, it´s just a question, if the gain is measurable, and worth the effort.
It takes effort to build a proper profile (wing) in this small scale.

IMHO

P.S. : How is your OCP suspension coming along?

[mep]

Why do you not start with a calculation done by hand?
I don't understand why people always want to do either CFD or FEM when some quick calculations by hand can also tell you many things.

Start with this:

L=1/2 * p * CL * A *v²

L= lift [N]
p= air density = 1,22 kg/m³
A= wing area [m²]
v= speed [m/s]
CL = coefficient of lift

http://en.wikipedia.org/wiki/Lift_(force)
http://en.wikipedia.org/wiki/Drag_(physics)

You know all the required data’s. For CL you choose your profile and angle of attack. Then you can read out CL and CD (coefficient of drag) from some profile graphs. They are quite easy to get in the net.
For example here:
http://www.worldofkrauss.com/foils/33
Search around a bit. There are many sides like this.

[marcush.]

is there any regs of how big your wing may be??? total height of bodywork total width etc?



maybe this will give you a bit trust to try and work out something:
toyota AAR prototype ,Aero developed with first a 10% model later with a 20% model.you have to love it..


http://www.prototyp.org/car/mkiii/20020 ... index.html
http://www.prototyp.org/car/mkiii/20020 ... s_002.html

http://www.grandtouringprototype.com/ph ... ow=gallery

[wesley123]

I love its design, the car was the best of the field, and the funny thing is, it wasnt even complex.

The MK.III was such an simple car, but making the simple things work well and also detailed wind tunnel testing can prove well, wich was proven by this car.

As you see on the shots they made the models incredibly detailed.

But OT; I think you should rather do some easy windtunnel tests, also you can post the design here with the car together. It is just how you want to build it, an wing adds drag, that is an fact, but it can also increase downforce

[marcush.]

i´m pretty sure they do not regulate were to put the downforce ...so it would be the cool thing to link the wing directly to the uprights ,avoiding the hassle of ahving to adjust the spring force....just an idea..

[747heavy]

well not sure what is in vouge today, but when I last raced R/C cars (o.k 20 years back ), it was not uncommon to have the rear spoiler connected to the rear uprights.

[747heavy]

Hi Peter,

not sure if you are a member of this forum here. (I´m sure you know about it)
it´s like F1technical for R/C cars.

Here a post from the forum (maybe it´s you )

>>>>
I have played with ground effect and I am amazed what it does at just 50km/h. A full size epoxy plate just fitting in width and length under the body with only holes for the wheels and flywheel screwed against the chassis. Although you can not scale down aerodynamic laws the effects are still there and the needed forces can be scaled down due the weight of a RC car.

I do believe a rear wing created in the right way as a reversed airplaine wing will work much better than a simple piece of lexan mounted on piano wire as we had in the old days. The problem is if manufacturers and organisations are willing to yake that step. A lexan wig is much simpeler and cheaper to make than a real looking car with good aerodynamics.....

Somewhere on this forum there is a project about adding small aerodynamic shaped parts on the chassis and lower wishbones....
__________________
Speed is only fiction but a 130+km/h MRS4 is for real.

<<<<

you can find it here:

http://www.rctech.net/forum/

and there is a thread discussing DAX suspension as well
http://www.rctech.net/forum/nitro-road/ ... ion-5.html

http://www.youtube.com/watch?v=VYDuSdeKn-8&NR=1
http://www.youtube.com/watch?v=U_w5FCDKbHM

[Peter-RC]

How is your OCP suspension coming along?

it's occuping space in my brain at the moment... haven't spend much energy on it so far.

[747heavy]

Hi Peter,

just come across this and thought, you may like it

Good luck

http://www.iaeng.org/publication/WCE200 ... 8-1591.pdf